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UNIT-8UNIT-8SCIENCE & SCIENCE &

TECHNOLOGY OF TECHNOLOGY OF NANOMATERIALNANOMATERIAL

SS

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S. S. No.No.

ModuleModule LectuLecture re No.No.

PPT Slide PPT Slide No.No.

11 Introduction. Nano Introduction. Nano science and science and

Nano technology Nano technology

L 1-2L 1-2 4-104-10

22 Fabrication of Nano Fabrication of Nano materials materials

L 3L 3 11-1411-14

3.3. Physical and chemical Physical and chemical Properties of nano Properties of nano materials.materials.

L 4L 4 15-1815-18

4.4. Carbon Nano tubes & Carbon Nano tubes & Applications.Applications.

L 5L 5 19-4119-41

UNIT INDEXUNIT INDEX

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APPLIED PHYSICSAPPLIED PHYSICS

CODE : 07A1BS05CODE : 07A1BS05

I B.TECHI B.TECH

CSE, IT, ECE & EEECSE, IT, ECE & EEE

UNIT-8UNIT-8

NO. OF SLIDES :41NO. OF SLIDES :41

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SCIENCE & SCIENCE & TECHNOLOGY OF TECHNOLOGY OF NANO MATERIALSNANO MATERIALS

Nanoscience can be defined as Nanoscience can be defined as the study of phenomena and the study of phenomena and manipulation of materials at manipulation of materials at

atomic, molecular and atomic, molecular and macromolecular scales, where macromolecular scales, where properties differ significantly properties differ significantly from those at a larger scale.from those at a larger scale.

Lecture-1

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Nano means 10-9. A nanometre (nm) is Nano means 10-9. A nanometre (nm) is one thousand millionth of a metre ( i.e. 10-one thousand millionth of a metre ( i.e. 10-9). Atoms are extremely small and the 9). Atoms are extremely small and the diameter of a single atom can vary fromdiameter of a single atom can vary from

0.1 to 0.5 nm depending on the type of the 0.1 to 0.5 nm depending on the type of the element. For example, one carbon atom is element. For example, one carbon atom is approximately 0.15 nm in diameter. The approximately 0.15 nm in diameter. The radius of the atom can be considered as radius of the atom can be considered as half the distance between neighbouring half the distance between neighbouring atoms when they are present in the solid atoms when they are present in the solid phase.phase.

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NanotechnologyNanotechnology

Nanotechnology can be defined Nanotechnology can be defined as the design, characterization, as the design, characterization, production and application of production and application of structures, devices and systems structures, devices and systems by controlling shape and size at by controlling shape and size at the nanometre scale.the nanometre scale.

Lecture-1

Lecture-1

Lecture-2

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All materials are composed of grains, All materials are composed of grains, which in turn comprise of many which in turn comprise of many atoms. Depending on the size, these atoms. Depending on the size, these grains may be visible or invisible to grains may be visible or invisible to the naked eye. Conventional materials the naked eye. Conventional materials have grains of size varying from have grains of size varying from hundreds of microns to centimeters. hundreds of microns to centimeters. Any bulk material we take, its size Any bulk material we take, its size can be expressed in three dimensions. can be expressed in three dimensions.

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Any planar material we take , its Any planar material we take , its area can be expressed in two area can be expressed in two dimensions. Any linear material we dimensions. Any linear material we take, its length can be expressed in take, its length can be expressed in one dimension. Nanomaterials could one dimension. Nanomaterials could be defined as those materials which be defined as those materials which have structured components with have structured components with size less than 100 nm at least in one size less than 100 nm at least in one dimension.dimension.

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Materials that are nanoscale in one Materials that are nanoscale in one dimension (and are extended in the dimension (and are extended in the other two dimensions) are layers, other two dimensions) are layers, such as thin films or surface such as thin films or surface coatings.coatings.

Materials that are nanoscale in two Materials that are nanoscale in two dimensions (and are extended in one dimensions (and are extended in one dimension) include nanowires and dimension) include nanowires and nanotubes.nanotubes.

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Materials that are nanoscale in three Materials that are nanoscale in three dimensions are particles, for dimensions are particles, for example precipitates, colloids and example precipitates, colloids and quantum dots (tiny particles of quantum dots (tiny particles of semiconductor materials). semiconductor materials). Nanocrystalline materials, made up Nanocrystalline materials, made up of nanometre-sized grains, also fall of nanometre-sized grains, also fall into this category.into this category.

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Production of NanomaterialsProduction of Nanomaterials Materials can be produced that are Materials can be produced that are

nanoscale in one dimension (for nanoscale in one dimension (for example, very thin surface coatings), example, very thin surface coatings), in two dimensions (for example, in two dimensions (for example, nanowires and nanotubes) or in all nanowires and nanotubes) or in all three dimensions (for example, three dimensions (for example, nanoparticles). nanoparticles).

Lecture-3

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Nanomaterials can be synthesised by Nanomaterials can be synthesised by 'top down' techniques, producing 'top down' techniques, producing very small structures from larger very small structures from larger pieces of material. One way of doing pieces of material. One way of doing this is mechanical crushing of solid this is mechanical crushing of solid into fine nanopowder (ball milling).into fine nanopowder (ball milling).

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Nanomaterials may also be Nanomaterials may also be synthesised by 'bottom up' synthesised by 'bottom up' techniques, atom by atom or techniques, atom by atom or molecule by molecule. One way of molecule by molecule. One way of doing this is to allow the atoms or doing this is to allow the atoms or molecules arrange themselves into a molecules arrange themselves into a structure due to their natural structure due to their natural properties e.g. Crystals grown.properties e.g. Crystals grown.

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Preparation of Nanomaterials:Preparation of Nanomaterials: Now there are many known methods to Now there are many known methods to

produce nanomaterials. produce nanomaterials. i) i) Plasma arcingPlasma arcing ii) ii) Chemical Vapour Deposition Chemical Vapour Deposition

(CVD) (CVD) iii) iii) Sol-GelsSol-Gels iv) iv) ElectrodepositionElectrodeposition v) v) Ball MillingBall Milling

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Nano materials have a relatively larger Nano materials have a relatively larger surface area when compared tosurface area when compared to

the same volume (or mass) of the the same volume (or mass) of the material produced in a larger form. Let material produced in a larger form. Let us us consider a sphere of radius "r",consider a sphere of radius "r",

Lecture-4

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Quantum confinement effectsQuantum confinement effects: : We know how energy bands are We know how energy bands are

formed. When atoms are isolated the formed. When atoms are isolated the energy levels are discrete. When energy levels are discrete. When very large number of atoms are very large number of atoms are closely packed to form a solid, the closely packed to form a solid, the energy levels split and form bands. energy levels split and form bands. Nanomaterials represent Nanomaterials represent intermediate stage.intermediate stage.

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We have studied the problems of We have studied the problems of particles in a potential well as well particles in a potential well as well as in a potential box. When the as in a potential box. When the dimensions of such wells or boxes dimensions of such wells or boxes are of the order of de Broglie are of the order of de Broglie wavelength of electrons or mean wavelength of electrons or mean free path of electrons (i.e. within few free path of electrons (i.e. within few tens of nanometre), energy levels of tens of nanometre), energy levels of electrons change. This effect is electrons change. This effect is called Quantum confinement.called Quantum confinement.

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When the material is in sufficiently When the material is in sufficiently small size typically 10 nanometers or small size typically 10 nanometers or less, organization of energy levels less, organization of energy levels into which electrons can climb or fall into which electrons can climb or fall change. Specifically, the change. Specifically, the phenomenon results from “electrons phenomenon results from “electrons and holes” being squeezed into a and holes” being squeezed into a dimension that approaches a dimension that approaches a critrical quantum measurement, critrical quantum measurement, called the "exciton Bohr radius." called the "exciton Bohr radius." These can affect the optical, These can affect the optical, electrical and magnetic behaviour of electrical and magnetic behaviour of materials, particularly as the materials, particularly as the structure or particle size approaches structure or particle size approaches the smaller end of the nanoscale.the smaller end of the nanoscale.

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Carbon Nanotubes (CNTs)Carbon Nanotubes (CNTs) Carbon nanotubes were first observed Carbon nanotubes were first observed

by Sumio Iijima in 1991. So far we know by Sumio Iijima in 1991. So far we know only three forms of carbon, namely only three forms of carbon, namely diamond, graphite, and amorphous diamond, graphite, and amorphous carbon. Now we come to know that carbon. Now we come to know that there is a whole family of other forms of there is a whole family of other forms of carbon known as Carbon nanotubes, carbon known as Carbon nanotubes, which are related to graphite. which are related to graphite.

Lecture-5

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The molecular structure of graphite is The molecular structure of graphite is one atom-thick a planar network of one atom-thick a planar network of interconnected hexagonal rings of interconnected hexagonal rings of carbon atoms. In conventional graphite, carbon atoms. In conventional graphite, the sheets of carbon are stacked on top the sheets of carbon are stacked on top of one another. They can easily slide over of one another. They can easily slide over each other. That is why graphite is not each other. That is why graphite is not hard, and can be used as a lubricant. hard, and can be used as a lubricant. When graphite sheets are rolled into a When graphite sheets are rolled into a cylinder and their edges joined, they cylinder and their edges joined, they form carbon nanotubes. i.e. form carbon nanotubes. i.e. Carbon Carbon nanotubes are extended tubes of nanotubes are extended tubes of rolled graphite sheets.rolled graphite sheets.

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Carbon nanotubes have assumed an Carbon nanotubes have assumed an important role because of their novel important role because of their novel chemical and physical properties. They chemical and physical properties. They areare

mechanically very strong (their mechanically very strong (their Young's modulus is over 1 Young's modulus is over 1 terapascal, making CNTs as stiff as terapascal, making CNTs as stiff as diamond),diamond),

flexible (about their axis), and can flexible (about their axis), and can conduct electricity extremely-well.conduct electricity extremely-well.

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Applications of Nanomaterials Applications of Nanomaterials :-:-

Nanoparticles are "the small Nanoparticles are "the small particles with a big future. Because particles with a big future. Because of their extremely small particle size, of their extremely small particle size, they have extremely large specific they have extremely large specific surface area. Hence they are surface area. Hence they are chemically very active. They are chemically very active. They are stronger and more ductile. They stronger and more ductile. They have electronic states quite have electronic states quite different from those of bulk.different from those of bulk.

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In dispersed state nanoparticles are In dispersed state nanoparticles are used as fillers, paints, magenetic used as fillers, paints, magenetic recording media, ferrofluids, drugs, recording media, ferrofluids, drugs, phosphors, phosphors, rocket propellant, fuel rocket propellant, fuel addittives etc.addittives etc.

ln consolidate state nanoparticles ln consolidate state nanoparticles are used as catalysits, electodes of are used as catalysits, electodes of solar cells and fuel cells, sensors, solar cells and fuel cells, sensors, adsorbents, synthetic bone, self adsorbents, synthetic bone, self cleaning glass etc.cleaning glass etc.

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In ordered assembly form In ordered assembly form nanoparticles are used as quantum nanoparticles are used as quantum electronic devices, photonic crystals, electronic devices, photonic crystals, DNA chips, biosensors etc.DNA chips, biosensors etc.

In very dense phase nanoparticles In very dense phase nanoparticles are used in synthesis of are used in synthesis of flexible/dense ceramics and flexible/dense ceramics and insulators, harder metals etc.insulators, harder metals etc.

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i) Materials Technology:i) Materials Technology: Magnets made of nanocrystailine Magnets made of nanocrystailine

yttrium-samarium_cobalt grains yttrium-samarium_cobalt grains posess unusual mangentic posess unusual mangentic properties due to their extremery properties due to their extremery large grain interface area. High large grain interface area. High coercivity can be obtained because coercivity can be obtained because magnetization flips cannot easily magnetization flips cannot easily propagate past the grain propagate past the grain boundaries. This could lead to boundaries. This could lead to applications in motors, analytical applications in motors, analytical instruments like magnetic resonance instruments like magnetic resonance imaging (MRI).imaging (MRI).

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ceramics are hard, brittre and ceramics are hard, brittre and difficurt to machine. However, with difficurt to machine. However, with a reduction in grain size to the a reduction in grain size to the nanoscare, ceramic ductility can be nanoscare, ceramic ductility can be increased.zirconia, normally a hard, increased.zirconia, normally a hard, brittle ceramic, has even been brittle ceramic, has even been rendered superplastic (for example, rendered superplastic (for example, able to be deformed up to 3oo% of able to be deformed up to 3oo% of its original length)its original length)

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Nanocrystalrine ceramics, such as silicon Nanocrystalrine ceramics, such as silicon nitride and silicon carbide, have been nitride and silicon carbide, have been used in such automotive applications as used in such automotive applications as high-strength springs, ball bearings and high-strength springs, ball bearings and valve lifters, because they can be-easily valve lifters, because they can be-easily formed and machined formed and machined , as well as , as well as exhibiting excellent exhibiting excellent chemical and high chemical and high temperaturetemperature properties. They are also properties. They are also used as components in high-temperature used as components in high-temperature furnaces.furnaces.

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Nanosized titanium diozide and Nanosized titanium diozide and zinc oxide are currently used in sun zinc oxide are currently used in sun -screens. They absorb and reflect -screens. They absorb and reflect ultraviolet (uv) rays and yet are ultraviolet (uv) rays and yet are transparent to visible light.transparent to visible light.

Nanosized iron oxide is present in Nanosized iron oxide is present in some lipsticks as a pigment.some lipsticks as a pigment.

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An important use of nanoparticles and An important use of nanoparticles and nanotubes in composites. Composite nanotubes in composites. Composite materials combine one or more materials combine one or more separate components and are designed separate components and are designed to exhibit overall the best properties of to exhibit overall the best properties of each component. Currently, carbon each component. Currently, carbon fibres and bundles of multi-walled fibres and bundles of multi-walled CNTs are used in composites having CNTs are used in composites having potential long-term applications.potential long-term applications.

carbon nanoparticles act as fillers in a carbon nanoparticles act as fillers in a matrix; for example, they are used as a matrix; for example, they are used as a filler to reinforce car tyres.filler to reinforce car tyres.

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Clay particle based composites-Clay particle based composites-containing plastics and nano-sized flakes containing plastics and nano-sized flakes of clay are also finding applications such of clay are also finding applications such as use in car bumpers.as use in car bumpers.

Recently developed applications include Recently developed applications include the self-cleaning windows. Nano coating the self-cleaning windows. Nano coating of highly activated titanium dioxide is of highly activated titanium dioxide is highly hydrophobic (water repellent) and highly hydrophobic (water repellent) and antibacterial. Coatings based on antibacterial. Coatings based on nanoparticulate oxides catalytically nanoparticulate oxides catalytically destroy chemical agentsdestroy chemical agents

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Wear and scratch-resistant hard Wear and scratch-resistant hard coatings are significantly improved coatings are significantly improved by nanoscale intermediate layers (or by nanoscale intermediate layers (or multilayers) between are hard outer multilayers) between are hard outer layer and the substrate material. layer and the substrate material. The intermediate layers give good The intermediate layers give good bonding and graded matching of bonding and graded matching of elastic and thermal properties, thus elastic and thermal properties, thus improving adhesion improving adhesion

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Improved control of porosity at the Improved control of porosity at the nanoscale has important nanoscale has important applications. A range of enhanced applications. A range of enhanced textiles, such as breathable, textiles, such as breathable, waterproof and stain resistant waterproof and stain resistant fabrics, have been enabled by this fabrics, have been enabled by this technique in variety of polymers technique in variety of polymers and inorganics.and inorganics.

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Other novel, and more long-term, Other novel, and more long-term, applications for nanoparticles lie in applications for nanoparticles lie in paints that change colour in paints that change colour in response to change in temperature response to change in temperature or chemical environment, or paints or chemical environment, or paints that have reduced infrared that have reduced infrared absorptivity and so reduce heat absorptivity and so reduce heat loss.loss.

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Nanoparticles react with pollutants in Nanoparticles react with pollutants in soil and groundwater and transform soil and groundwater and transform them into harmless compounds . Iron them into harmless compounds . Iron nanoparticles transform chlorinated nanoparticles transform chlorinated hydrocarbons (which are carcinogens) hydrocarbons (which are carcinogens) into less harmful end products in into less harmful end products in groundwater. Iron nanoparticles could groundwater. Iron nanoparticles could be used to transform heavy metals such be used to transform heavy metals such as lead and mercury from bio available as lead and mercury from bio available forms into insoluble forms.forms into insoluble forms.

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Information TechnologyInformation Technology Nanoscale-fabricated magnetic materials Nanoscale-fabricated magnetic materials

also have applications in data storage. If also have applications in data storage. If the area required to record one piece of the area required to record one piece of information can be shrunk in the information can be shrunk in the nanoscale (and can be written and read nanoscale (and can be written and read reliably), the storage capacity of the disk reliably), the storage capacity of the disk can be improved dramatically. The can be improved dramatically. The devices on computer chips which operate devices on computer chips which operate using flows of electrons could use the using flows of electrons could use the magnetic properties oi these electrons, magnetic properties oi these electrons, called spin, with numerous advantages.called spin, with numerous advantages.

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Coatings with thickness controlled at the Coatings with thickness controlled at the nano or atomic scale have been used in nano or atomic scale have been used in opto electronic devices or in catalytically opto electronic devices or in catalytically active and chemically functionalized active and chemically functionalized Surfaces.Surfaces.

CNTs are beinginvestigated for CNTs are beinginvestigated for lowvoltagefield emission displays;their lowvoltagefield emission displays;their strength, sharpness, conductivity and strength, sharpness, conductivity and inertness make them potentially very inertness make them potentially very efficient and long-lasting emitters.efficient and long-lasting emitters.

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Nanocrystalline zincselenide, zinc Nanocrystalline zincselenide, zinc sulphide and lead telluride telluride sulphide and lead telluride telluride synthesized by sol-gel techniques synthesized by sol-gel techniques are candidates for the next are candidates for the next generation of light emitting generation of light emitting phosphors, they will have huge phosphors, they will have huge market for large area, high market for large area, high brightness, flat-panel displays ( as brightness, flat-panel displays ( as used in television screen and used in television screen and computer monitors)computer monitors)

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Nanoparticles are used for Nanoparticles are used for information storage information storage

Quantum electronic devices have Quantum electronic devices have started replacing bulky started replacing bulky conventional devices.conventional devices.

Nano dimensional photonic crystals Nano dimensional photonic crystals are used in chemical/optical are used in chemical/optical computers.computers.

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Biomedicals :-Biomedicals :- Nanocrystalline zirconium oxide(zirconia) Nanocrystalline zirconium oxide(zirconia)

is hard,wear resistant,bio- corrosion is hard,wear resistant,bio- corrosion resistant and bio-compatible. If therefore resistant and bio-compatible. If therefore presents an attractive alternative material presents an attractive alternative material for implants. It and other nanoceramics for implants. It and other nanoceramics can also be made used as strong, light can also be made used as strong, light aerogels by sol-gel techniques. aerogels by sol-gel techniques. Nanocrystalline silicon carbide is a Nanocrystalline silicon carbide is a candidate material for artificial heart candidate material for artificial heart valves primarily because of its low valves primarily because of its low weight, high strength and inertness.weight, high strength and inertness.

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Contlrolled drug delivery is possible Contlrolled drug delivery is possible using nanotechnology. Diffusion of using nanotechnology. Diffusion of medicine through nanoporous polymer medicine through nanoporous polymer reservoir as per the requirement is reservoir as per the requirement is very useful in controlling the disease.very useful in controlling the disease.

Nano strucured ceramics readily Nano strucured ceramics readily interact with bone cells and hence interact with bone cells and hence finds application as an implant finds application as an implant materialmaterial